## Identical Binary Trees (Same Tree) problem

Given two binary trees, write a function to check if they are the same or not.

Two binary trees are considered the same if they are structurally identical and the nodes have the same value.

Example 1:

``````Input:     1         1
/ \       / \
2   3     2   3

[1,2,3],   [1,2,3]

Output: true
``````

Example 2:

``````Input:     1         1
/           \
2             2

[1,2],     [1,null,2]

Output: false
``````

Example 3:

``````Input:     1         1
/ \       / \
2   1     1   2

[1,2,1],   [1,1,2]

Output: false
``````

## Identical Binary Trees (Same Tree) problem solution in Java

The problem can be solved easily using recursion. Two binary trees are identical if:

• their root nodes have the same value,
• their left subtree is identical,
• their right subtree is identical.

Here is the complete solution in Java:

``````class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode(int val) {
this.val = val;
}
}

class SameTree {
private static boolean isSameTree(TreeNode a, TreeNode b) {
if (a == null && b == null) {
return true;
}

if (a == null || b == null) {
return false;
}

return a.val == b.val &&
isSameTree(a.left, b.left) &&
isSameTree(a.right, b.right);
}

public static void main(String[] args) {
TreeNode a = new TreeNode(1);
a.left = new TreeNode(2);
a.right = new TreeNode(3);

TreeNode b = new TreeNode(1);
b.left = new TreeNode(2);
b.right = new TreeNode(3);

System.out.println(isSameTree(a, b));
}
}
``````